The present invention relates to the field of photography and, more specifically, to improvements in motion picture apparatus.
Recently, a motion picture system has been developed wherein a motion picture camera, projector and portable viewer are configured for use with a plurality of separate card-like film units, each having a plurality of sequential images thereon, rather than the conventional continuous film strip supplied on a reel.
The camera is disclosed in commonly-assigned copending applications U.S. Ser. No. 047,204 filed on June 11, 1979 by Philip R. Norris and Richard R. Wareham and entitled "Card Motion Picture System"; and U.S. Ser. No. 047,115 filed on June 11, 1979 by Philip R. Norris and entitled "Card Motion Picture Camera".
The projector and portable viewer are disclosed, respectively, in commonly-assigned copending applications U.S. Ser. No. 047,141 filed on June 11, 1979 by Philip R. Norris and entitled "Card Motion Picture Projection System"; and U.S. Ser. No. 047,057 filed on June 11, 1979 by Philip R. Norris and entitled "Portable Card Motion Picture Viewer".
The camera employs a scanning optical system including a movable portion that traverses across the film plane to record an arcuate row of sequential images on a portion of the film unit and a film advance system for incrementally advancing the film unit one row position after each traverse for recording the next successive arcuate row of images as the movable portion traverses in the opposite direction. Similar scanning optical systems and film advance systems are employed in the projector and viewer for playback.
The transparency film unit is preferably of a self-developing type having a format similar to film units manufactured by Polaroid Corporation, Cambridge, Massachusetts for use in SX-70 Land Cameras. With its generally square snapshot sized image area, approximately 200 sequential Super 8 image frames may be recorded thereon providing 10-12 seconds of running time for each recorded scene. Successive scenes are recorded on separate film units so that the motion picture may be easily edited for projection by changing the order of the individual film units.
The scanning optical system employed in the camera comprises a fixed portion including a focusing lens mounted on the camera housing for transmitting image-forming light along a first optical axis and a movable portion mounted on a pivoting periscope boom having its pivot axis, at one end, aligned with the first optical axis. The optical elements on the boom include a mirror and primary lens for transmitting light from the objective lens along a second axis substantially perpendicular to the first axis, and a second mirror for reflecting this light along a third axis, substantially parallel to the first axis, through an aperture stop or moving gate on the opposite or optical output end of the boom to the film plane.
The boom is pivotally mounted on a plate having an arcuate row of spaced exposure apertures therein, aligned with the arcuate path of travel of the output end of the boom, through which the portion of the film unit, located below the plate at the film plane, is exposed. These exposure apertures serve as a fixed gate for defining a plurality of image positions at the film plane.
The camera also includes means in the form of a barrel cam and cam follower coupled to the boom for advancing the output end stepwise along a given locus on the arcuate path to sequential imaging locations which correspond in number and spacing to the exposure apertures so that at each step, where the boom is stopped for exposure, the imaging location defined by the boom optics is a registration with a corresponding one of the imaging positions defined by one of the fixed gate exposure apertures.
Because the given locus of travel of the moving gate and the spacing of the sequential imaging locations along the locus are fixed by a double helix groove on the barrel cam, the question of whether or not the moving gate aperture will be in registration with the corresponding fixed gate apertures depends on how accurately the barrel cam is positioned along its axis line with respect to the fixed gate apertures. That is, if the barrel cam is not properly positioned on the axis line, the moving gate will be misregistered with each of the fixed gate apertures during its stepwise traverse along the fixed gate.
To insure such registation, not only does the barrel cam itself have to be accurately machined, but the members mounting it for rotation must be made to very close tolerances for proper axial placement thereby significantly increasing the cost of manufacture of the camera.
In the interests of reducing the manufacturing costs, it is highly desirable, and an object of this invention, to eliminate the need for such high tolerance mounting members and provide a means for adjusting the location of the given locus for accurate registration after the boom, barrel cam, and cam follower have been assembled on the fixed gate plate.